A variety of interlocking type masonry building blocks are available for the construction of load bearing and non-load bearing walls. Such blocks are laid in courses without the use of mortar as done in conventional masonry. As a general rule, conventional masonry wall blocks are heavy and relatively difficult to handle. Such blocks typically include projections that mate with corresponding indentations on adjacent blocks. However, many of these projections are relatively small and thus there is an inherent weakness in the block. Also the use of small projections and small indentations means that the blocks have to be built to close tolerances which makes the blocks more expensive. The typical small projections may be easily broken or chipped off prior to or during construction which means that many blocks are discarded adding to the expense. Further the available blocks do not have suitable provision for the installation of embedded utilities. Thus there is a need for masonry wall blocks that are relatively light and easier to handle, that are cost effective to manufacture and easily assembled into a more stable and dependable wall structure with provisions for embedding utilities.
An early example of typical approaches to an interlocking block wall is disclosed in a U.S. Pat. No. 3,382,632 of Grafsik. As disclosed therein a block construction wherein a plurality of blocks are assembled together by means of cooperating projections and cavities formed in the blocks and suitable tie rods screw the blocks together under vertical tension to provide a sturdy wall construction. The tie rods extend transversely through vertical passages in each block and are adapted to be engaged by the tie rods for securing layers of the blocks together in vertical tension.
A more recent U.S. Pat. No. 6,105,330 of Nanayakkara discloses a construction component for use in a wall structure. The component is capable of resisting high gravity and lateral loads and is defined by a partially hollow building block having a generally solid rectangular exterior configuration in which one entire end surface of the building block exhibits a positive deep key geometry and the opposing end surface exhibits a negative deep key geometry complement to the positive geometry of the opposite end. The deep key interlocks also exhibit between opposing horizontal block surfaces as positioned between vertical cavities as the block narrows in the negative direction. In addition, there is created a substantially rugged and load resilient interlock between vertical and horizontal complementary surfaces when joined as components of a wall structure.
Notwithstanding the above, it is presently believed that there is a need and a potential commercial market for the building blocks and wall structures according to the present invention. There should be a need and a potential market for such masonry building blocks because they are strong, will support heavy vertical loads and at the same time are relatively light weight. In addition, the masonry building blocks in accordance with the present invention have a high resistance to wind and other lateral forces and can be manufactured and sold at a competitive price. Still further, the weight and cost of such blocks are further reduced by the elliptical vertical passageways extending through the blocks.